System Drop-in Tests of R-134a Alternative Refrigerants ARM-42a and R-1234ze(E) in an Air- Cooled Screw Chiller and a Water-cooled Centrifugal Chiller

Transcription

1 System Drop-in Tests of R-134a Alternative Refrigerants ARM-42a and R-1234ze(E) in an Air- Cooled Screw Chiller and a Water-cooled Centrifugal Chiller Satheesh Kulankara, William McQuade, Scott Rauch and Justin Kauffman Building Efficiency Johnson Controls

2 Overview Introduction Overall Approach to Evaluation Air-Cooled Screw Chiller Details and Test Results Water-Cooled Centrifugal Chiller Details and Test Results Summary 2

3 Introduction This presentation covers results from the testing of lower GWP refrigerant alternatives for R-134a in chillers Two lower GWP refrigerants were tested and compared against R-134a ARM-42a (GWP < 150, azeotropic mixture, R-134a/R-152a/R-1234yf (7/11/82% by mass) R-1234ze(E) (GWP = 6, single component) Both refrigerants are classified as A2L per ASHRAE 34 Two types of chillers were evaluated Variable speed air-cooled screw chiller Variable speed water-cooled centrifugal chiller Testing was conducted to optimize both full load and integrated part load efficiency (IPLV) IPLV is described in AHRI 550/590 3

4 Overall Approach to Testing Two types of tests as defined in the AREP handbook were conducted Drop-in tests of ARM-42a in air-cooled screw chiller and water-cooled centrifugal chiller Drop-in tests of R-1234ze(E) in water-cooled centrifugal chiller Soft-Optimized tests of ARM-42a and R-1234ze(E) in water-cooled centrifugal chiller Test conditions followed AHRI 550/590 requirements All tests were conducted sequentially No modifications were made to the chillers during the course of testing Same instrumentation was used for all tests Soft-Optimized tests on the centrifugal chiller were tests with varying compressor speeds Data was averaged over a minimum of 15 minutes of steady state operation 4

5 Air-Cooled Screw Chiller Configuration Economized cycle Variable speed screw compressor Micro-channel condenser coils Falling film evaporator Electronic expansion valves POE oil Both refrigerants were tested with the same compressor speed at full load 5

6 Air-Cooled Screw Chiller Drop-In Test Results (ARM-42a) TEST # % CAPACITY AIR TEMP ( F) Ratio The full load capacity of the chiller with ARM-42a was equal to that with R-134a The part load of the chiller at 50% was different for the two refrigerants due to the number of fans operating. Chiller control was optimized for R-134a. It is possible to optimize chiller controls to improve at 50% to match R- 134a 6

7 Water-Cooled Centrifugal Chiller Configuration Variable speed centrifugal compressor Magnetic bearings Pre-rotation vanes Shell and tube condenser External subcooler Flooded evaporator Oil free chiller 7

8 Water-Cooled Centrifugal Chiller Drop-In Test Results With R-1234ze(E) Compressor speed that result in highest full load with R-134a was held constant for all tests Full load capacity of the chiller with R-1234ze(E) drop-in is 8.8% lower % CAPACITY R-134a R-1234ze(E) Ratio IPLV

9 Water-Cooled Centrifugal Chiller Soft-Optimized Test Results With R- 1234ze(E): Maximum IPLV Compressor speed optimized for each test condition to get maximum IPLV for each refrigerant Full load capacity of the chiller with R-1234ze(E) is 19.5% lower % CAPACITY R-134a R-1234ze(E) Ratio IPLV

10 Water-Cooled Centrifugal Chiller Soft-Optimized Test Results With R- 1234ze(E): Maximum Full Load Compressor speed optimized for each test condition to get maximum full load efficiency for each refrigerant Full load capacity of the chiller with R-1234ze(E) is 8.8% lower % CAPACITY R-134a R-1234ze(E) Ratio IPLV

11 Water-Cooled Centrifugal Chiller Drop-In Test Results With ARM-42a Compressor speed that result in highest full load with R-134a was held constant for all tests Full load capacity of the chiller with ARM-42a drop-in is 14.2% higher % CAPACITY R-134a ARM-42a Ratio IPLV

12 Water-Cooled Centrifugal Chiller Soft-Optimized Test Results With ARM-42a: Maximum IPLV Compressor speed optimized for each test condition to get maximum IPLV for each refrigerant Full load capacity of the chiller with ARM-42a is equal % CAPACITY R-134a ARM-42a Ratio IPLV

13 Water-Cooled Centrifugal Chiller Soft-Optimized Test Results With ARM-42a: Maximum Full Load Compressor speed optimized for each test condition to get maximum full load for each refrigerant Full load capacity of the chiller with ARM-42a is 14.2% higher % CAPACITY R-134a ARM-42a Ratio IPLV

14 ARM-42a SUMMARY Variable speed air-cooled screw chiller Equal capacity 3.5% lower full load efficiency Equal IPLV possible with changes to chiller control Variable speed water-cooled centrifugal chiller A range of design options with capacity ranging from equal to 14% higher Full load efficiency with ARM-42a is 8.5 to 9.7% lower IPLV is 9.0 to 16.3% lower Possible improvements in compressor and heat exchanger designs to increase chiller efficiency need to be evaluated 14

15 R-1234ze(E) SUMMARY Only tested in a variable speed, water-cooled centrifugal chiller A range of design options with capacity ranging from 9 to 20% lower Full load efficiency ranges from 0.6 to 5.8% lower IPLV ranges from 0.7% higher to 5% lower Possible improvements in compressor and heat exchanger designs to increase chiller efficiency need to be evaluated 15